Figure 1.

A depiction of isoprenoid synthesis through the core 6 enzyme MVA and 7 enzyme MEP pathways. Also depicted are the newly discovered archaeal branches from the MVA pathway. The thermoarchaeal-type branch begins with mevalonic acid whereas the archaeal and haloarchaeal-type branches stem from MVAP. Typically, isoprenoids are synthesized by acetyl-CoA, pyruvate, and G3P, however IPP and DMAPP can also be synthesized from C5 alcohols, D-ribulose or D-ribulose-5-phosphate, and a synthetic route in which HMG-CoA is ultimately converted to prenol. AibAB, 3-methylglutaconyl-coenzyme decarboxylase; AtoB, acetyl-CoA acetyltransferase; BMD, bisphosphomevalonate decarboxylase; cbjALD, 3-methylcrotonyl-CoA reductase; DXR, 1-deoxy-D-xylulose 5-phosphate reductase; DXS, 1-deoxy-D-xylulose 5-phosphate synthase; HMGR, 3-hydroxy-3-methylglutaryl-CoA reductase; HMGS, 3-hydroxy-3-methylglutaryl-CoA synthase; IDI, isopentenyl diphosphate isomerase; IPK, isopentenyl phosphate kinase; IspD, 2-C-methyl-D-erythritol 4-phosphate cytidylyltransferase; IspE, 4-diphosphocytidyl-2-C-methyl-D-erythritol kinase; IspF, 2-C-methyl-D-erythritol 2,4-cyclodiphosphate synthase; IspG, 4-hydroxy-3-methylbut-2-enyl diphosphate synthase; IspH, 4-hydroxy-3-methylbut-2-enyl diphosphate reductase; LiuC, 3-hydroxy-3-methylglutaryl CoA dehydratase; M3K, Mevalonate 3-kinase; M3P5K, Mevalonate 2-phosphate-kinase; nDXP, 1-deoxyxylulose-5-phosphate synthase; PMD, phosphomevalonate decarboxylase; PMK, phosphomevalonate kinase; tAHMP, anhydromevalonate diphosphate decarboxylase; ThiM, hydroxyethylthiazole kinase; XK, xylulose kinase; YahK, aldehyde reductase.